#!/usr/bin/env python
#
# Copyright (C) 2013  Google Inc.
#
# This file is part of YouCompleteMe.
#
# YouCompleteMe is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# YouCompleteMe is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with YouCompleteMe.  If not, see <http://www.gnu.org/licenses/>.

import imp
import os
import threading
from ycmd.utils import ForceSemanticCompletion
from ycmd.completers.general.general_completer_store import (
    GeneralCompleterStore )
from ycmd.completers.completer_utils import PathToFiletypeCompleterPluginLoader


class ServerState( object ):
  def __init__( self, user_options ):
    self._user_options = user_options
    self._filetype_completers = {}
    self._filetype_completers_lock = threading.Lock()
    self._gencomp = GeneralCompleterStore( self._user_options )


  @property
  def user_options( self ):
    return self._user_options


  def Shutdown( self ):
    with self._filetype_completers_lock:
      for completer in self._filetype_completers.itervalues():
        if completer:
          completer.Shutdown()

    self._gencomp.Shutdown()


  def _GetFiletypeCompleterForFiletype( self, filetype ):
    with self._filetype_completers_lock:
      try:
        return self._filetype_completers[ filetype ]
      except KeyError:
        pass

      module_path = PathToFiletypeCompleterPluginLoader( filetype )
      completer = None
      supported_filetypes = [ filetype ]
      if os.path.exists( module_path ):
        module = imp.load_source( filetype, module_path )
        completer = module.GetCompleter( self._user_options )
        if completer:
          supported_filetypes.extend( completer.SupportedFiletypes() )

      for supported_filetype in supported_filetypes:
        self._filetype_completers[ supported_filetype ] = completer
      return completer


  def GetFiletypeCompleter( self, current_filetypes ):
    completers = [ self._GetFiletypeCompleterForFiletype( filetype )
                   for filetype in current_filetypes ]

    for completer in completers:
      if completer:
        return completer

    raise ValueError( 'No semantic completer exists for filetypes: {0}'.format(
        current_filetypes ) )


  def FiletypeCompletionAvailable( self, filetypes ):
    try:
      self.GetFiletypeCompleter( filetypes )
      return True
    except:
      return False


  def FiletypeCompletionUsable( self, filetypes ):
    return ( self.CurrentFiletypeCompletionEnabled( filetypes ) and
             self.FiletypeCompletionAvailable( filetypes ) )


  def ShouldUseFiletypeCompleter( self, request_data ):
    """
    Determines whether or not the semantic completer should be called, and
    returns an indication of the reason why. Specifically, returns a tuple:
    ( should_use_completer_now, was_semantic_completion_forced ), where:
     - should_use_completer_now: if True, the semantic engine should be used
     - was_semantic_completion_forced: if True, the user requested "forced"
                                       semantic completion

    was_semantic_completion_forced is always False if should_use_completer_now
    is False
    """
    filetypes = request_data[ 'filetypes' ]
    if self.FiletypeCompletionUsable( filetypes ):
      if ForceSemanticCompletion( request_data ):
        # use semantic, and it was forced
        return ( True, True )
      else:
        # was not forced. check the conditions for triggering
        return ( self.GetFiletypeCompleter( filetypes ).ShouldUseNow(
                   request_data ), False )

    # don't use semantic, ignore whether or not the user requested forced
    # completion
    return ( False, False )


  def GetGeneralCompleter( self ):
    return self._gencomp


  def CurrentFiletypeCompletionEnabled( self, current_filetypes ):
    filetype_to_disable = self._user_options[
        'filetype_specific_completion_to_disable' ]
    if '*' in filetype_to_disable:
      return False
    else:
      return not all([ x in filetype_to_disable for x in current_filetypes ])

